Research On Sensorless Detection And Control Of Bearingless Permanent Magnet Synchronous Motor

A bearingless permanent magnet synchronous motor(BPMSM)is a new type of motor which combines traditional motors and magnetic bearings.This kind of motor not only has the advantages of no mechanical friction and wear,no lubrication or sealing required,no pollution,high speed,high precision and long life,but also has the advantages of high power density,simple structure and non-excitation winding.So the BPMSM has broad application prospects in equipment such as precision high-speed motorized spindle,flywheel energy storage and so on.In order to make sure the stable rotation and suspension operation of the BPMSM,it is necessary to detect the rotor speed and displacements accurately.These sensors not only increase the axial volume but also reduce the reliability of the system which limit the applications in high-speed or ultra-high-speed fields.Therefore,it is of great significance to research the speed and displacement sensorless technology of the BPMSM.Sponsored by Key Research and Development Program of Jiangsu Province(BE2016150),the mathematical models,speed sensorless technology,displacement sensorless technology,digital control system,experimental platform are studied.The main works and achievements of this dissertation are as follows:1.The research background and development trends of the BPMSM are described systematically.Then,the generation mechanism of torque and radial suspension force are analyzed.The mathematical models of torque and radial suspension force are derived by using the method of magnet circuit and field virtual displacement,respectively.2.A composite control method for the BPMSM is proposed.In low speed or standstill,the pulse high frequency signal injection method based on generalized second-order integrator(SOGI)is used to solve the problem of signal delay and phase offset caused by using the high order filter.On the basis of the improved back-EMF observer,the generalized second-order integrator frequency-locked phase-locked loop(SOGI-FLL-PLL)is used to detect the speed and position in medium or high speed.The simulation platform of the composite control system is built in the MATLAB,and the feasibility of the method is verified.The simulation results show that the control method can estimate the position and speed accurately in different speed ranges,and has good dynamic performance.3.A suspension force windings magnetic linkage identification module based on improved generalized second-order integrator is proposed.Firstly,based on the inductance matrix model,the relationship between magnetic linkage and radial displacement of suspension force winding is deduced.Then,the displacement sensrroless method is explored.Finally,the simulation platform of the displacement sensorless method is built in the MATLAB.The simulation results verify the correctness and reliability of the system.4.In this dissertation,the hardware and software of the BPMSM are studied.The experiment control platform is built and the related experiment researches are carried out.